Kinetics of ozone reaction with uric acid, ascorbic acid, and glutathione at physiologically relevant conditions

This study quantified the reaction kinetics of O3 with three low molecular weight antioxidants—uric acid (UA), ascorbic acid (AH2), and glutathione (GSH)—found in respiratory mucous. Using a semi-batch reactor in which a 500 ml/min flow of air containing 1–5 parts per million of O3 contacted 3 ml of well-stirred physiological saline solution containing 100–200 μM antioxidant, we found that: (1) mass transfer resistances in the gas and liquid phases were successfully eliminated by the reactor design; (2) the reaction of O3 with UA, AH2 and GSH had stoichiometries of 1:1, 1:1, and 1:2.5, respectively; (3) the reactivity between O3 and antioxidants was in the order UA ≈ AH2 > GSH. Simulating the measured amounts of O3 absorbed and antioxidant consumed with a mathematical model, reaction rate constants of O3 with UA, AH2, and GSH were found to be 5.83 × 104 M−1 s−1, 5.5 × 104 M−1 s−1, and 57.5 M−0.75 s−1, respectively.